Aqulaculture pens are used for the farming of marine animals in natural bodies of water such as scas or rivers. Aquaculture pens typically comprise a floating frame from which a net is suspended, the net defining or forming an enclosure for confining the marine animals to be fanned. The size of the pens can vary considerably but pens having a diameter of 40-50 meters are not uncommon. The pens are anchored in a sea or river so that the marine animals are harvested in an environment similar to that in which they would normally live. Typically the pens are attended to every day for the purposes of feeding and animal husbandry. The current method for harvesting or examining the marine animals held within the pen is archaic, labour intensive and expensive. A typical scenario for harvesting marine animals is for a team of two or three divers to dive into the pen and physically herd the marine animals into each other so that they can be grabbed by hand. Indeed, commonly, when the marine animals are fish, they are physically grabbed by the gills by the divers and then acted upon as necessary.
It is also known to place a pen adjacent the pen holding the animals and for the divers to cut the nets of both pens, stitch them together, and then herd a predetermined number or otherwise selected group of animals into the second pen and then separate and restitch the pens. This may be done to separate animals of different size or other different characteristics.
It will be appreciated that because of the large volume of water bound by the pens the above described method of harvesting and otherwise handling the marine animals is extremely inefficient, labour intensive and expensive.
It is also known that due to the fragile psyche of marine animals, a significant percentage often die through trauma when being harvested in the above mentioned manner. Current estimates are that up to 5% of the marine animals may die due to stress when harvested or handled in this manner.
Hitherto, it had also been thought that the above type of aquaculture pen had little deleterious effect on the environment. It was believed that the natural sea currents and wave motion would clear away the waste products front the pens, which includes the faeces of the animals and uneaten food. However this does not always occur. It is known that storms can cause waste products on the sea bottom to pass through a pen poisoning the captive marine animals. Studies have revealed that the waste products by and large settle beneath the pens on the sea bed have the effect of; killing natural sea grasses; promoting the growth of selected species of marine animals over others to effect the overall ecological balance; and, potentially acting as a poison for the, marine animals held within the pens.